How Evolution Made Nature’s Perfect Winemaker
on 23/05/11 at 9:26 amWine
Yeasts are diverse—biologists estimate that there are at least 1,500 different species of the fungal microorganisms. But when it comes to fermenting wine, one yeast is much more common than any other. The same is true in brewing and baking—food and drink chemists overwhelmingly prefer Saccharomyces cerevisiae.
How did this one species earn most favored yeast status? Cellular biologists at Lund University in Sweden used genetic sequencing to study several kinds of yeasts and have found evidence that S. cerevisiae underwent a series of rDNA changes 100 to 200 million years ago. This evolution helped S. cerevisiae outperform its fellow yeasts and dominate the fermentation of wine and beer.
When S. cerevisiae, present either on grape skins or added by winemakers, comes in contact with grape must, it instantly begins to consume the sugars, primarily glucose and fructose. In doing so, it produces alcohol, carbon dioxide, heat, and other compounds to make wine. It also avoids breaking down the antioxidants and other organic compounds associated with wine’s health benefits. But it’s the alcohol production that is the key to this yeast’s success.
S. cerevisiae is not the only yeast that does this. So do species such as Dekkera bruxellensis, which separated from the S. cerevisiae lineage nearly 200 million years ago. “But it wasn’t until the emergence of the modern fruit humans consume today, around 150 million years ago, that the two became direct competitors,” said Jure Piskur, a cell and organism biology professor at Lund University and lead author of the report, which was published this month in the journal Nature Communications.